All Forum Comments
Comment by johnwhit posted on Value of SMC Pentax- A *300mm f/4? at 20/08/2010 - 19:29
Hi Graham, I have the FA 28/2.8, it is a different design to all other 28mm Pentax lenses and IMHO the equal best optically the other being the K 28/3.5. Well worth spending a little to have it serviced. All my lens service/repairs have been handled by Michael Spencer, factory trained 47 years experience, if it can be cleaned then he's your man!
Very friendly and helpful, ring him for a chat and advice 01246 250767
cleaning a lens usually costs approx £25 including return postage Special Delivery, never had a problem
http://www.camerarepairs-r-us.co.uk/
Regards,
John
Very friendly and helpful, ring him for a chat and advice 01246 250767
cleaning a lens usually costs approx £25 including return postage Special Delivery, never had a problem
http://www.camerarepairs-r-us.co.uk/
Regards,
John
Comment by johnwhit posted on Pentax FA28/2.8 disassembly at 20/08/2010 - 11:48
http://www.bobatkins.com/photography/technical/field_of_view.html
Probably the most common is the equisolid angle projection, and the FOV at infinity focus is given by:
FOV (equisolid fisheye) = 4 * arcsin (frame size/(focal length * 4))
Also popular is the equidistance projection, and for the the field of view is given by:
FOV (equidistance fisheye) = (frame size/focal length)*57.3
(the 57.3 is to convert from radians to degrees).
Less common are the orthogonal projection which gives the following field of view:
FOV (orthogonal fisheye) = 2 * arcsin (frame size/(focal length *2)
and the stereographic projection which gives:
FOV (stereographic fisheye) = 4 * arctan (frame size/(focal length * 4))
Regards,
John
Probably the most common is the equisolid angle projection, and the FOV at infinity focus is given by:
FOV (equisolid fisheye) = 4 * arcsin (frame size/(focal length * 4))
Also popular is the equidistance projection, and for the the field of view is given by:
FOV (equidistance fisheye) = (frame size/focal length)*57.3
(the 57.3 is to convert from radians to degrees).
Less common are the orthogonal projection which gives the following field of view:
FOV (orthogonal fisheye) = 2 * arcsin (frame size/(focal length *2)
and the stereographic projection which gives:
FOV (stereographic fisheye) = 4 * arctan (frame size/(focal length * 4))
Regards,
John
Comment by johnwhit posted on Wide Angle or Fish Eyes? at 20/08/2010 - 10:58
Congratulations Tim
Regards,
John
Regards,
John
Comment by johnwhit posted on First photo in PPG Premier Collection! at 19/08/2010 - 09:48
Nice work, really like #2
John
John
Comment by johnwhit posted on First Macro at 18/08/2010 - 18:16
Offertonhatter wrote:
A K20D mk2 (or should that be a K10D mk3!)
Magnesium bodied like the K-7
3" screen
K-7 shutter on it (quieter and less recoil than the K20D shutter)
at least 6fps, maybe 7fps (and an increase of fps to 7-8 with grip, ala Nikon)
Bigger buffer and faster write speeds
SR switch on the back (not on the K-7)
faster more accurate AF
more than 11 AF points, maybe with 3d tracking.
more precise metering (the K20D can under expose, the K-7 can over expose)
Low light/hi ISO performance like the k-x
Full weather sealing will be a given.
lockable dial from the K-7 as so many times I have accidently moved it on the K20D
If a tilt screen can be provided without compromising weather sealing would be nice.
twin card slots would be nice too, but as long as will take SDXC then that might not be an issue.
improve the 14.6 APS-C even more, no point trying to go to 18mp.
1/250 flash sync
100% VF
electronic level.
So, basically taking the best of each model and putting it into a new K20D model, plus some improvements generally.
Yep, that would do nicely and keep it under £1000A K20D mk2 (or should that be a K10D mk3!)
Magnesium bodied like the K-7
3" screen
K-7 shutter on it (quieter and less recoil than the K20D shutter)
at least 6fps, maybe 7fps (and an increase of fps to 7-8 with grip, ala Nikon)
Bigger buffer and faster write speeds
SR switch on the back (not on the K-7)
faster more accurate AF
more than 11 AF points, maybe with 3d tracking.
more precise metering (the K20D can under expose, the K-7 can over expose)
Low light/hi ISO performance like the k-x
Full weather sealing will be a given.
lockable dial from the K-7 as so many times I have accidently moved it on the K20D
If a tilt screen can be provided without compromising weather sealing would be nice.
twin card slots would be nice too, but as long as will take SDXC then that might not be an issue.
improve the 14.6 APS-C even more, no point trying to go to 18mp.
1/250 flash sync
100% VF
electronic level.
So, basically taking the best of each model and putting it into a new K20D model, plus some improvements generally.
John
Comment by johnwhit posted on Whats new at 15/08/2010 - 19:24
Lovely set Tim 3 and 6 for me
Regards,
John
Regards,
John
Comment by johnwhit posted on Cambridge (6 images) at 13/08/2010 - 09:18
Regards,
John